1. Field of the Invention
The present invention relates generally to a positioning apparatus of a mobile terminal using a positioning server independently constructed on a network and a method thereof, and more particularly to a positioning apparatus and method of a mobile terminal using a positioning server independently constructed on a network, such that the positioning of a roaming mobile terminal using an SUPL (Secure User Plane Location) using an IP (Internet Protocol)-based network is performed. Additionally, the present invention is applicable to a positioning service on a control plane in addition to a positioning service on a user plane.
2. Description of the Related Art
As mobile terminals become more lightweight and small-sized, users' abilities to carry and use their mobile terminals have increased. Additionally, under the environment of a global mobile communication system, many users intend to receive application services (for example, traffic and living information) using position information of the mobile terminals. Accordingly, in some countries or mobile communication network territories (for example, territories of Korean mobile communication networks such as SK Telecom, KTF, or Japanese and European mobile communication networks such as NTT DoCoMo, Sprint PCS, KDDI, or Vodafone), mobile terminal position information acquisition systems using such mobile terminals have already been commercialized.
In order to provide the application services using position information, as described above, a process of positioning a mobile terminal should precede. That is, the application services using position information should be provided based on geographical position information of the mobile terminal, which is obtained in the process of positioning the mobile terminal.
FIG. 1 schematically illustrates a conventional mobile communication system. In particular, FIG. 1 illustrates a GSM (Global System for Mobile communication) or UMTS (Universal Mobile Telecommunication System) mobile communication system.
Referring to FIG. 1, the UMTS mobile communication system includes a CN (Core Network) 110, a plurality of RNSs (Radio Network Subsystems) 120 and 130, and a UE (User Equipment) 150. The CN 110 manages information of the UE 150, and performs mobility management, session management, and call management. As such, the RNS 120 or 130 includes an RNC (Radio Network Controller) and a plurality of base stations (i.e., node Bs). For example, the RNS 120 includes an RNC 121, a node B 123, and a node B 125, and the RNS 130 includes an RNC 131, a node B 133, and a node B 135.
The RNCs 121 and 131 can be classified as a serving RNC (SRNC), a drift RNC (DRNC), or a controlling RNC (CRNC) according to their operation. That is, the RNC that manages information of UEs that belong to the corresponding RNC and controls data transmission between UEs and the CN 110 through an interface lu is called an SRNC. The RNC that relays data transmission between the UE belonging to another RNC and the RNC to which the UE belongs (for example, an SRNC) is called a DRNC. The RNC that controls the respective base stations (i.e., node Bs) is called a CRNC.
In FIG. 1, if the RNC 121 manages the information of the UE 150, it operates as the SRNC of the UE 150. If the UE 150 moves and the UE 150 and the RNC 121 transmit and receive data through the RNC 131, the RNC 131 operates as the DRNC of the UE 150. The RNC 121 that controls the base station (i.e., node B) 125, which is communicating with the UE 150, becomes the CRNC of the base station 125. The information and data of the UE 150 is transmitted to the CN 110 through the RNC 121 that is the SRNC of the UE 150.
In the mobile communication network as described above, diverse positioning techniques for positioning the UE have been used, and three representative techniques will be described herein below.
A first method performs the positioning of the UE in the unit of a cell using information of a cell that is the nearest cell to the UE or that manages the UE. A second method is a network-based positioning method for calculating the strength of a signal using a measurement signal between the node B and UE or a time of arrival (TOA) or a time difference of arrival (TDOA), which is obtained from the transfer time of radio waves, and positioning the UE by applying a triangular surveying method to the TOA or TDOA. A third method for positioning the UE uses a GPS (Global Positioning System) developed by the United States Department of Defense. By supplementing and applying the GPS-technology among the positioning method using the GPS to a mobile communication system, a network-assisted GPS (network-AGPS) has been proposed.
Conventionally, if a location service client (LCS client) outside a network requests the position of a specified UE, a preparatory process for performing the positioning of the UE is performed, a signal required for the positioning is measured, and the position of the UE is calculated according to the measured signal. More specifically, in the preparatory process, a privacy indicator such as a privacy limit of the UE is examined, resources of the network are allocated, and a positioning technique is selected according to a QoS (Quality of Service) requested by an LCS client and the performance of the UE and the network.
Additionally, the position measurement process is performed between a UTRAN (Universal Terrestrial Random Access Network) and the UE, such that the signal required for the position measurement is acquired according to the positioning technique selected in the preparatory process, and then the position of the UE is calculated. In this case, the UE should be an individual UE for which the MSISDN (Mobile Subscriber ISDN Number) or IMSI (International Mobile Subscriber Identity) is already known.
The position measurement process described above is frequently performed if the UE deviates from a home gateway mobile location center (GMLC) at which the UE itself is registered in the CN and is located at another GMLC, or if the positioning service is requested by an external LCS client or the UE itself. In this case, the GMLC manages position information of UEs located in PLMN (Public Land Mobile Network). A PLMN is a geographically or logically separable mobile communication network, and at least one GMLC may exist in one PLMN.
FIG. 2 is a flowchart illustrating a conventional method of positioning a mobile terminal. In particular, FIG. 2 illustrates the positioning process if the external LCS client (hereinafter referred to as a ‘client’) 160 requests the position of the UE_A 155.
Referring to FIG. 2, the client 160 requests the location service (LCS) for the UE, of which the client 160 wants to know the position, to a connected GMLC 111 in step S11. That is, the client 160 requests the position information of the UE_A 155. Because the GMLC 111 requests the position of the UE_A 155, it is represented as a ‘requesting GMLC’ in FIG. 2.
The requesting GMLC 111 requests the home PLMN information of the UE_A 155 from an HLR/HSS (Home Location Register/Home Subscriber Server) 115 in step S13, and receives the home PLMN information from the HLR/HSS 115 in step S15. The HLR/HSS 115 is a server that stores registrants information and roaming information of the stored UEs, and responds to the request of the requesting GMLC 111 using the stored registrants information of the UEs. That is, the HLR/HSS provides the home PLMN information of the UE_A 155 to the requesting GMLC 111 in step S15.
The requesting GMLC 11 that has received the home PLMN information of the UE_A 155 at step S15 requests the information about the PLMN in which the UE_A 155 is located from the home GMLC 113 of the UE_A 155 using the home PLMN information in step S17. The home GMLC 113 performs a privacy authentication process in step S19, receives visited PLMN information of the UE_A 155 from the HLR/HSS 115 in steps S21 and S23, and requests the position information of the UE_A 155 from the GMLC 117 of the PLMN that the UE_A 155 is visiting, using the visited PLMN information in step S25. Because the GMLC 117 is the GMLC of the PLMN that the UE_A 155 is visiting, it is called a ‘visited GMLC’.
The visited GMLC 117 in the PLMN that the UE_A 155 is visiting, an MSC/SGSN (Mobile-services Switching Center/serving GPRS (General Packet Radio Service) Support Node) 119, a RAN (Radio Access Network), and the UE_A 155 calculate the position of the UE_A 155.
Typically, in the mobile communication network, a positioning method such as a cell identification technique, a TDOA technique, an A-GPS technique, etc., is used as described above. Accordingly, the PLMN that the UE_A 155 is visiting can measure the position of the UE_A 155 using any one of the three methods.
Meanwhile, the measurement of the position performed by the above-described methods may be classified into two methods according to the burden of network resources or the subject of position calculation. That is, the position measurement method may be classified into a UE-based method for calculating the position of the UE itself, using pseudo-range information and positioning-assisted information, and a UE-assisted method for obtaining pseudo-range information using a GPS satellite signal acquisition assistant data (for example, A-GPS assistant data) and then transferring the pseudo-range information to the corresponding RNC that manages the LCS service of the UE for the network's calculation of the position of the UE.
In the process illustrated FIG. 2, the UE_A position information request transferred to a visited GMLC 17 of the UE_A 155 is transmitted to the RAN 170 through the MSC/SGSN 119. If the corresponding RNC sends the A-GPS assistant data of the UE_A 155 to the UE_A 155 and the UE_A 155 calculates the position of the UE_A 155 itself, the position measurement method is UE-based. However, if the UE_A 155 sends the GPS pseudo-range information obtained by the UE_A 155 to the RNC and the network calculates the position of the UE_A 155, the position measurement method is UE-assisted.
If the position of the UE_A 155 is calculated by one of the UE-based and UE-assisted methods in step S27, the visited GMLC 117 transfers its result (i.e., the position information of the UE_A) to the home GMLC 113. The home GMLC 113 performs the authentication process again at step S31, and then transfers the position information of the UE_A 155 transferred from the visited GMLC 117 to the client 160 through the requesting GMLC 111 in steps S33 and S35.
FIG. 3 is a block diagram schematically illustrating a conventional network for performing the positioning of a mobile terminal. Referring to FIG. 3, in order to provide the mobile terminal positioning service, the network should include a positioning service permission module and a position calculation service module. For example, in order to perform the positioning of a terminal A (not illustrated) in a state in which the terminal A deviates from a home network 210 and is roaming to a visited network 220, the home network 210 and the visited network 220 should include a positioning service permission modules 211 and 221, and position calculation service modules 213 and 223, respectively. The positioning service permission modules 211 and 221 (for example, LMUs) perform the authentication of the mobile terminal subject to positioning and a privacy protection function, and support data transmitted between HLR and VLR in order to perform the authentication and privacy protection function. Further, the position calculation service modules 213 and 223 (for example, PDE (Position Determination Entity) perform an assistant data generation related to the position calculation and a calculation process.
Accordingly, the home network 210 that has received the request for the position information of the terminal A authenticates the position information request and the privacy protection function of the terminal A. If it is possible to respond to the position information request, the home network 210 requests the position information of the terminal A from the position calculation service module 223 of the visited network 220 using the position calculation service module 213, and then calculates the position of the terminal A after receiving the response to the position information request.
However, the conventional method of positioning the mobile terminal as described above, has the drawbacks in that if there is no position calculation system (for example, LMU (Location Measurement Unit), or PDE) that is additionally provided according to mobile communication service providers in the network, it cannot provide the positioning service according to the request of the external LCS client or mobile terminal.
Consequently, if the network that is not provided with the position calculation system receives the positioning service request from the mobile terminal, it must respond with a failure to the request or use the position calculation system provided another network by accessing the network that can prove the positioning service.
However, in using the position calculation system provided in another network that can provide the positioning service, the network that can provide the positioning service may reject the use permission of the position calculation system or may exclusively use the positioning system.
Additionally, when a home network performs the positioning of a mobile terminal that deviates from the home network and is located in another network, the accuracy of assistant data to be transferred to the terminal may deteriorate. This causes the accuracy of the positioning to deteriorate if the positioning is performed using the PDE.